Question

A girl of mass 30 kg climbs up a flight of 20 steps each 10 cm high in 3 minutes and a boy of identical mass does the same in 2 minutes. Compare the a) work done b) power developed by them.​

Answer 1

Explanation:

Given: m1=40kgf,m2=30kgf,h1=h2,t1=4minutes=4×60sec,t2=3minutes=3×60sec

Comparing work done by them:

Work done by girlWork done by a boy=m2gh2m1gh1=m2m1=3040=4:3

(ii) Comparing power developed by them:

Power developed by girlPower developed by boy=Work done by girl / time taken to climb up the stairs in secondsWork done by boy / time taken to climb up the stairs in seconds

                                   =3×6018004×602400

                                  =4×602400×180